New mp3 options and improved encoding performance

Source/LibationUiBase/SampleRateSelection.cs

@@ -0,0 +1,18 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace LibationUiBase
+{
+	public class SampleRateSelection
+	{
+		public AAXClean.SampleRate SampleRate { get; }
+		public SampleRateSelection(AAXClean.SampleRate sampleRate)
+		{
+			SampleRate = sampleRate;
+		}
+		public override string ToString() => $"{(int)SampleRate} Hz";
+	}
+}